1. Field of the Invention
The present invention relates to a structure of a terminal of an occupant detection sensor mounted on a vehicle seat and to a structure of a connector containing the terminal.
2. Description of the Background Art
An occupant detection system includes, for example, a capacity type sensor, a connector, and an occupant detection ECU (electronic control unit). The capacity type sensor outputs turbulence of a weak electric field generated at an electrode as a current or a voltage as described, for example, in Unexamined Japanese Application Publication No. 2006-27591 A. The occupant detection ECU determines, based on the current or the voltage output from the capacity type sensor, whether or not an occupant sits on a vehicle seat.
A connector is provided at an end of the capacity type sensor. The connector internally makes electric connection between the capacity type sensor and the occupant detection ECU. The capacity type sensor is mainly mounted inside the vehicle seat. The connector at the end of the capacity type sensor is also disposed inside or near the seat. Therefore, the connector needs to be waterproof against intrusions from liquids such as spilled juice, normal saline, rain, seat cleaning liquids and the like, so as to protect the connector inside against water or liquid exposure. FIGS. 8A and 8B show the structure of a conventional connector. FIG. 8A is a plan view of the connector with a cover 104 removed. FIG. 8B is a front view thereof with the cover 104 in FIG. 8A mounted.
The conventional connector includes a case 103 having a circular opening 103a and the cover 104 to cover the opening 103a. The opening 103a is recessed at the center of a top surface of the case 103. The opening 103a contains a terminal, hereafter referred to as an ECU terminal, electrically connecting to an occupant detection ECU (not shown). A circular first packing 105 is attached to an end face of the opening 103a. A corresponding circular second packing 106 is also attached to the cover 104.
An end 122 of the capacity type sensor, hereafter referred to as a sensor end, is disposed so as to be sandwiched between the first packing 105 and the second packing 106. A terminal 123 is formed at the sensor end 122 and contacts with an ECU terminal (not shown) in the case 103.
Conventionally, a width of the sensor end 122 in a horizontal direction of FIG. 8B is smaller than widths of the first packing 105 and the second packing 106 at their outside ends in the horizontal direction of FIG. 8B so that the connector can contain the sensor end 122.
According to the conventional structure, however, a thickness of the sensor end 122 in a vertical direction of FIG. 8B causes gaps A near both sides of the sensor end 122 left and right in FIG. 8B, such as at positions surrounded by the sensor end 122, the first packing 105, and the second packing 106. The gap A passes through the outside and the inside of the connector along the sensor end 122 and thus inhibits the waterproof integrity or waterproof performance of the connector. As will be widely appreciated, water exposure may short-circuit a terminal in the connector.
One solution to the above described problem includes a scenario where the first packing 105 and the second packing 106 can be made of a highly flexible material such as silicone gel. The silicone gel can transform so as to enter and fill the gap A. Since the silicone gel is expensive, however, production costs increase.